SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6234e62d3d174f185ed435c65d514a3628fcba8d6721fc6d1e4bc47e228a156d' 
  AND token = 'NBflY0srSekWox+VvaB/PqhVmJsB7pOgKg0IJwllTeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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