SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da08d5d3a9af87adb69c505151478e059f7a413609b636967ed3b0dcd2bd050a' 
  AND token = 'fBxR11AHw4HhO+pRyRdv1RitFTsW44oAsK8qMfPdM7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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