SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ec0bea50dda63fe81e37060c959b819bca283bdf454cd936f4928442d1c7245' 
  AND token = 'UNazPAMovmC6+60y/yo5i/QRf24TZQAFXBSOe075rDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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