SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f685eace18707549e2171d6ea58527b05f3581e3eb90753374a0787812c8f74a' 
  AND token = 'At46MmqGF7FcIJG77/MwSKs3WN/Hsv9XvUdjSID+sjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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