SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f3ceadcca4fd942bee3942bfa42ef5d4e1e30a506fb05bbaa914a6f853a2a7e' 
  AND token = 'NnbrHGPErgWrqRb/Dod1IQqRQWefvGWxs/n8XQcesjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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