SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fa2a4591152490ec08c2691dc5771240931b54e8249d994a8fdc98acd5a3496' 
  AND token = 'QJl+AsbkKdISMUgNWOca8NzkaZbuRqdVWNQLY/JYt0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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