SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '829b1d1bde3643c261c93d22c8aa8f870c19179cab3b751bd989a91f0c47bce8' 
  AND token = 'XoBTJ9/iSHiurp6ndbsdktM9EyatIyZ+OavVcWBYidQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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