SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '526eacc0c0e2bd068e3712dd13218dd67dee0e44be853016e9207e552362cc43' 
  AND token = 'o65cA2EIzoEeKVyRzFUuNPtmSsydAQsYtYOCV86JWGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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