SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '775557a0476551ac41f8f313d7ac0786983c347478dfbec78d168ab053bf9399' 
  AND token = '4Vr/GMRZDDcAEN1bTRN+WqMQwWq6+Ljeozjb6eJcsPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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