SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6f99fc1b021f4c11785cb42103d31e9de6c132881630ed01da2fbea53bf6df6' 
  AND token = 'BQbm/70bnAcrlZPJzoRFBLbxK0oAvPJkHIbfPQk7zf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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