SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f578f0e61905443a09f6baae8d9fb60eebf45fd06beddb37f5ed5175e0f799ae' 
  AND token = 'Ldu6sHVmTDcE5qLWusIwsm4i3P0W7L1JVdAKwDpJ9Wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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