SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64fd9c2b20440c58d4cd4cbf6ca5e6446b8824a4195a3209de3fae6dbe9881c1' 
  AND token = 'lme189PHVImGr6MFmBiOujrb88mPfLB9+u3BZFcN6qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}