SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ac75d2e4e401810727462cd47e8f13937a606fb1ed3be761c5cb971080e2f8b' 
  AND token = '7nEszh1pbb9XQwgOikvi+k6cbUgEQim1Wnd98amzIWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00094

JSON explain

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