SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '274969a10f9109fe945a5be34c2a59793a7cac63f011f6916b7556989d1ba39a' 
  AND token = '+lx8SZZ0TpKXpdnWTQlRElaQvZvOm0ALiXmnT3Y9Mto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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