SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a643d8f839834400792ad505456911675e8d5976b58ec2acb576d9239b81545' 
  AND token = 'wTuJWFCyv5h6yr62eI6Yfry1mEn7DTlBLRSaAuKd8fA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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