SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1510f2ad3de13b1d71687bc27567ae6534ec69b9b55a877f42166f5c98f2f8e' 
  AND token = 'JCGEnxjrkxnLOiYAZYy3FMwrCFKsikH0nd02C+b+Mfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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