SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '042b05f3324171a27a7a79838d58eb1a766fcb7c0bb4e31c2e9f5d36f6f39bcc' 
  AND token = '5aa8+m2LG2x5dEsjnQtJxjBRBvIZQ1/nZApQBKt1SDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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