SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87108e58e9d2ac9eb6bd5987f12936c1995883fd159446dd7864d482bc32553a' 
  AND token = 'UbX8GMNJqBpsOK4KrVzpdaN3gDMlAQIAkHpZlEYwBXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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