SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '329f11bf7f7d397387a565e2b5bfa3303119423868caab4d9d5be20268467787' 
  AND token = '7Fi2YxjAsQCbctLMKdqp1sSy+ZR6SuHn7aBzYEgy3lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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