SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '333646f51a05c6e3a5e172e890d207290be6a5f4848cbb47b1e58ebd64a0d079' 
  AND token = 'xJUB+H9y4JzoyYu+8ZuYgdZs1bOQgUjHgnqcupuGNsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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