SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1de9267785a295fe9a44b14e04e731adb24546ae98aba8081b8785bdba12a5b' 
  AND token = 'dwTjpqTd3vB/QH2jmOnykedulDUsyRw8nGKRDYZxPEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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