SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '52501d7752a510d03fa87cfae535a564bd081da3029ff7c6b5b131a0412f0b27' 
  AND token = 'h4uGr4RMKFt30wB+oFzKfieNXGa05C/6G2Vq8ez/feg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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