SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f80d923b55bf856f72942ab69d90e2925b774dc937646de0e06683ff27347b0' 
  AND token = 'r23fwkMGUunSBKXgU4Tesj+i71Kle0JQhmj5xmL/EmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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