SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bec948bc931ee8d254934f83648dd993f0ce2cc761cbb4f3038a5ebf2809445' 
  AND token = 'nB3oU5uEyHW+lw0z/vH+Hb2YHzQ4ZEVJhNSpJvFi4Mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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