SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5f139a353118071926037b0b390c70b23876ed33d2f1a0947ad9ef162c883b5' 
  AND token = 'gq+1bp4lwlJRS9GbptMsfK8XA/YgaHs1dDHiUKK8E5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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