SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd58a1fed65d4638b672b6859488cfc0d626af32669b3f64d9a1210628ec4209' 
  AND token = 'RCy2CLUgLVkhNWwEVblwmaFs7sUu/2/xf+KennzGVBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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