SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75008892c8dea17bb78f5c2c7a891b791c3811bf13392855c8dc83dfcc038b47' 
  AND token = 'QdcTYeTVzCVShoyKdnOnPVjzxGPxm+XKptauOUyS3Qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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