SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fa84b208b101f95862ba60c1e0353dd6f38e6fe2e99c8b9a2a07b780bc9305' 
  AND token = 'QQy3ERk4pWApPQwXiCDYSS7OIw8H4OvvWxvAosEcC50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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