SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3126d476ba89811efa6fc1f08944ab0716b1d0cfc144b4dcedd3dc4b45d51b57' 
  AND token = 'o/ZGfhBV+AStmwY5Dr8f2yGSqmwj+cyCxyoiVBS9Ado=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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