SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc348c731026cd8b55f303658b529939bcc5f6846a583efd206159ad31b3e86' 
  AND token = 'VkEQJVDdYyNAiOvCIMnR8CTzlhPLTGCJWG85qKT4abE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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