SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c8f2c8a118d5957993148f135c76085593ce3dca4be9ba2865aa154168941c4' 
  AND token = 'pSKtSg+h1sRLrCDpbvl2KeHnV8KRDNXXTordhllhhVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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