SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c5760369807114d3dc5e49c3edf1a6e236f48c5cd533a1638f8104bf59c8472' 
  AND token = '/j5/jtZEMYVJFgiNFqx8GpjWIsPPwQpXr6f3slCwyPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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