SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42620afae57476f7af9e6533025134cc94715460915417e7d2b194b34496feab' 
  AND token = 'UpdklQyQl4Cm/2z105IqJwsRSnVAewjBoMUUc3vjfgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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