SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e876b12c87b1385ce3fb0332666d026c643ce6ad8661c81031c8a9ab90d40069' 
  AND token = 'piln2zV7p/LxWOKNCTJBNo65+zUC8ba4vPg1/XcHb2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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