SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c018439ed075f3591b580316d2ecd38fba29628788ee09186926125c97b852' 
  AND token = '3PvpQwTs3OvGqS9pfZ+AEhgacCPhcCBw8QxYWoO/gys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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