SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8790043b382ddaf88a4929292b51643e58843a75e096a5c74abbca1b392e5c4a' 
  AND token = 'rSVmw0bdbH1OlSU/b4NJcAxuda+DcxeCjOwjb4vqgGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}