SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f8a15f2f5a19952f8b393101a3480ce28737d4f269246ef29cb2d2edfcc936d' 
  AND token = 'FjGdhPhnYkEQ+TuzlbVdfgrpJgZoRwPohwJo7Y2g3Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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