SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6d7c31b793d9132018d0d9d9abd357a73732f37430af1c900c702d0e8020015' 
  AND token = '0uAMCi8pIyLKFIxSrNmVDiBJvuwi/oPusbs1h/y7gIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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