SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '935cff1a3eaf144b735708d5392336cbd0d26acb2c1b7fcb0a33991f7b87a4ba' 
  AND token = 'MGmfjWdiMyIacr+Z/EQ55doT6hLmYPEqr72btQ4BvdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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