SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d34fe604c2ec94f87e8171f74bca88fa8ead32aca7d0977919df073fc5b412' 
  AND token = 'DYWCdMPVENm4YgNoic4XnyMDIesGJTUKRm2yRAGQpnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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