SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '545aa8e0f1ba9c59b1bdc4bfc66057cc0246857d34b08c74274b2c42296b626b' 
  AND token = 'fAuPKERg4SM4KMLc2kFsmFc0Tr1bKmMnpiBB4E8y3ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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