SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9d6eddf658b3012ff75c971bd060957595444961e4f5912ab21b37996b2aa44' 
  AND token = 'SkejAfQ3+zgLURn+jlKHzpE6TvDh47ToAWYTdeBO+Eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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