SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '751b3650c072797f4292264c455f62ea7c7cb3ed1573358ce32b96f083ae6d85' 
  AND token = 'XdbQQTvd+x+TrVsaOrVap64niFOMjaxI98ypAvK4SHw=' 
  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"
    }
  }
}