SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66de29611556d92e51a3f84fb81a15365cbad2386da8834703a7973b93e1d0af' 
  AND token = 'kK9uZM3fiTCHpgvqO2G1PQF9zWIgAQgJ13cBQIFwMjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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