SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b35717f18085491e6b9281863896c8821ac4dc2bade9ee000abacbefe06cc263' 
  AND token = 'owC4Q2Npuc3KJ5Ha5vaJHKvqlz+sPOPO//7MMAc8eck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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