SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2ea587c48342861ae8e4fe0af60e10e42112cf1ac0defa25cc98b410e5b8098' 
  AND token = 'E9VDepVcybhSiakCgL8MGB3nD5zBOmR4uMycMMEKxK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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