SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bfe696529aa4465e9f51fca8413cb388bf31c2f27ed13a2ae79fa7cde6239f4' 
  AND token = 'ON0f0NCCtxNXGFsT7YPJGFjBnO7GNVq4sfJmlUExzCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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