SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd81c9d66736e9079016741ca6e6a2065ab87dd2020da6591c7d619851bf16ce1' 
  AND token = '3/29cliHPtFaeN2Wc1oTyQx1HoYi9tuv8+q6u6i2fgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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