SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f19f914729598d86f538624576ab56cf3f3d95457758b0be225cef8ccff6d1b4' 
  AND token = 'Uv3lEXaAnwZY9rzC+2TJ8zOcM6k77bJ2jWTHFN6MBZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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