SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50125a5cacb8cbb7fa9bd66a10917f55508b961afdb2b2e853648dd39d068fe1' 
  AND token = 'pfc7AnWUQQM+DISB46NhkqHe8v6SZ4MM+nnO//Yr5QM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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