SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eac170e1c1f4cbbf6461ff3fbf3a7759d36015fbed0e3d716456eac955cdc2e' 
  AND token = 'x7iu3GDFLqgFlQ+uFOhKBVZUQvdTnCa8lU5Z/Dip+I0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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