SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5916f4c3eed2911563771be49d0754a12ed1d42b936f626af5030a6e027b81a3' 
  AND token = 'lKk6jmZ8gAmvp1WoG3/EasMKH4HsqMAHlcsSKc+i2/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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