SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c6997540fb7fb0bd810ff2a24d29fcd155bb05f12264ffbc9331affaba2086d' 
  AND token = 'ROIpjpUoLQ8LOpKZ+onykSGyrbhPf8Q3vlVbQOEiIxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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