SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '138ffb358b8b4b890472f74043291a39ad2a8b3dcd8606e552174ac34ec5a60f' 
  AND token = 'UfEQYwpgu44NH2q3R8msx810AHDeGC6OLx75foPPOhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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