SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b912a32d7975172253384cdfc11a5c1f2b5385ec925f3599f63651de5fab0791' 
  AND token = 'w6FQx+bsGgdkQy8wv2RSLGSjz2E+wun303lD1UhFhDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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