SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0a8c7e87cd491248cf043e4f376db8193586af8147dbb6e890c0342e188312f' 
  AND token = 'tMPUVsKxtMoClXfeQHWvpKIOhQ1byLP6+NDsTv1K2jg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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