SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b651b7c3f2c92797e83cff72bd0c6315d7af7234f5c498945a64e3387204e26' 
  AND token = 'uHT9Ep4QZGqGrfkKDFvayjXt3XHyqfkT0arc2sKp5r8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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