SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1973ddd650e0a12daa77c5ec18418efc9038362b3d1823e47f433acaa95602' 
  AND token = 'Mdn0ct6lq4uiEpSLNEqhSXTxH0JMLkm5jTydUatVsXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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