SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fd021e4eba99cabdc373d21229bcb588c6ba256265c5bd378e047123d58e598' 
  AND token = 'a5vijMinAw4su2CZKB4hVYK1Y8/GfPDJgY2Ss7/y+ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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