SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ebb02d15be53879a540426841325a2031fcc9a8eb5b762f4a4b8e3e91015a3' 
  AND token = 'wF2GOdnb6GzPjEfANvJGC6GB89K2kvud/tWNGfMTOCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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