SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e19ea8e4a7ffab5a308b4250f5be2471694237580b80bd6fd9cfcb0e39c8e610' 
  AND token = 'nEnu/3MNG6NtL3G341ZP7Y1ujBWd84HKdry7SQo9Lgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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