SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '720320dc7c11d5318846dc188c2fa99f6511eaa28a7cd016d3df89d6ca72971f' 
  AND token = 'RI+SJXQ9JpznXx89xzw75o5AkJDAq5G6nDVP6IhtRLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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