SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '845cbcbe7bf105917d7909589f3ecbea539891529c61fc466037f26db495b97a' 
  AND token = '7KGttGUvNDNHRCoViI1IpCok9kSw24VwOZs7pvTSBXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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