SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0d741d0f84c5b4d7a8346d546d94d0a3e64dcf543f13e38c25bbcecf1beb973' 
  AND token = 'fSr68NtB+fFgJAKWGGugwHsWqGCMA7Rg8bbYT+U5hQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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