SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c053626b0b714e48af5ae8dffd4d918a3f08a4ccce4c4bc23ff8f56c59735391' 
  AND token = 'RBz1QBviV1F5IS+tPIdilJNCR/xFkLwYCaLgSg05pOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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