SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8081c8656a39483fff6d340b4611e6f0f9433f69a99012e904d5714c1d85278a' 
  AND token = 'PIgzRJK5uiuLKKyFXZm2fB2vrDQO3XIw04Fq/D+u7Co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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