SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4a0a8fd4494ef74ce42e9a7be5b549490472c65721e5ee01e1c44d6ad8a17f6' 
  AND token = 'LU6uL2yGdKrFSSDrZOPZpy134DxsghNvEkVFoE1OJ0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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