SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8171e59e5f449632bc6aa319fd283e6eb6e880415f658e6f77785839c1d4c124' 
  AND token = 'oS9xyAKK+tVgwZrQPEGxU8JNm4ioksLVN+9mq4TSzUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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