SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408e8b105504ca9732325e732289e2243c1024cc6dad76d8fa7623adb5b12533' 
  AND token = 'pbwEKGthmwyoPVrkQpDstcxyd4QTzdtxFQ6VlQ3wvYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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