SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3714fb756ffb98404f4674ceed9bf113e31021eb3e3fb23112fc004fdfe6e2a' 
  AND token = '5whWQthStVMxHPMKxNfsR5QZ9iyP2HKrP9aoozVgOXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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