SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '644e1b0ef134290dae32809deebe4351e4849d687a0cfda96037a7a13187c8be' 
  AND token = 'eQ2f4XN6ULrB8jqirTsQSoq4BLA9WzdWPi7HPgYb37E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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