SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42bcdd316d3c8e9ebab2c1976318fdc80e076c6dd08ebdc5415948d3e2a08e18' 
  AND token = 'O/niZpbLHLh5os+66314WptZQFt/bFAs6TqWwc12e28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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