SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34b9779c1e0d3773d1a3885506b8cecdf60a9df77e9e1e65c41679551aebb364' 
  AND token = 't5hKx+7Gl/MnRCZeNfoJd/kvQKXgVy+2GgANFETxNB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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