SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08e7cdd0e6d059856ea73d3ae37b8da14b94444c2795ba4435728a1a10345abe' 
  AND token = '71IHVTxN1/PimKIjyUCCRK5rvp8iO7vyDFK+pgkKftY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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