SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f6c650ad5813cc5d194ba304409b4b87af916d699384441e1593e32fe77c248' 
  AND token = 'N9tpP+nsBPxLsqH5qkdJKeYoYnFyDOu48fdryT+VNuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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