SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f0b598e9f37124e0ce00a21fe5e23966c22a249d1fe9180ff698085d97ae799' 
  AND token = '+IQhJ9Bs7c/Djggm3GBim1rfuaKy2pBYQZ7Hj6OvvA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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