SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c185d9c690adcfdf4dd84322f044ab5739a881ef07e375b5a1c10ac0cc2d5af' 
  AND token = '42VPq0IUrHDai/SfmCZAgcrGvR51mRkcC6EtLV5+xCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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