SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dffe79e053caca82df039a09e18fad43fc97898c7a0a5e73aef1563e611fa772' 
  AND token = 'RfA1NMnDgc0+UkttCC30Kkl5jHAhQjV4QFT3gawSBpQ=' 
  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"
    }
  }
}