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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd878973f88a6d8a87572ccb714db96b15ef34cef37d973cf39a539473bee35a9' 
  AND token = 'vkZctQCDARDavXQb+8tj84qV1bdxRVn1XnPT9iHRczY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}