SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '386719528e510ebbaa29d753a9acb20836751c7a7d14a04b5689d323cf243776' 
  AND token = '6BCkSeRVwOvjxZ/q0O5BW8LVaw+NpsP9fty1Vp4nKAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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